1. Field of the Invention
In a distribution type fuel injection pump for an internal combustion engine, this invention relates to a device for automatically correcting a full load injection quantity by not only rpm of the engine but also the boost pressure and atmospheric pressure.
2. Description of the Prior Art
In the distribution type fuel injection pump, particularly the pump for direct-injection engine, the injection quantity characteristic is in the tendency of dropping in a high rotation zone relative to the pump speed by a throttling action of the nozzle. As a countermeasure, a negative angleichung device is incorporated, but there is a drawback that the correction cannot be made from the stroke-wise limitation, and for the correcting performance improvement, the full load injection quantity correcting device illustrated in FIG. 1 has been developed.
This device is constructed in such way that the maximum shifting position of the tension lever is changed by the pressure (the pressure and pump rpm are proportional) in the pump chamber (3) to prevent the dropping in the high rotation zone.
In a brief description of the distribution type fuel injection pump, a plunger (5) for distribution doubling as pump is slidably fitted in a sliding hole (1a), and this plunger (5) is caused to reciprocate and rotate by a means not illustrated in the drawing.
In case the plunger (5) is in a suction stroke which is a movement of left direction in the drawing, the fuel of the pump chamber (3) supplied from feeding pump (not shown) is sucked into a pump chamber (14) through one of suction grooves (13) whose number corresponds to the number of cylinders of the engine which are disposed equally on the outer periphery of the head portion of the plunger (5) by means of a supply path (11).
When the plunger (5) is shifted in feeding stroke which is a movement of right direction in the drawing, the supply path (11) and the suction groove (13) are separated, and the fuel in the pump chamber (14) is compressed and is supplied to one of distribution paths (17) from a distribution port (16) by means of a through hole (15) perforated in the plunger (5) in its axial direction and is sent to an injection nozzle not shown from a feeding valve (18), and is injected into the cylinder.
The full load injection quantity correcting device is constructed in such way that a piston (80) is provided to receive the pressure in the pump chamber (3), and the control characteristic is memorized as an inclined surface (80a) in this piston (80), and a sensor pin (81) abuts on the inclined surface (80a), and as the pressure in the pump chamber (3) is increased, and the piston (80) is shifted, the sensor pin (81) is placed according to this movement, and a lever (41) for determining the maximum shifting position of the tension lever is moved and the maximum shifting position of the tension lever (24) is changed.
However, when the full load injection quantity correcting device of this kind is provided, an atmospheric pressure correcting device and boost pressure correcting device are not provided, and there is a problem that the correction of the atmospheric pressure and the boost pressure cannot be made which is the drawback.